Parachuting by military personnel and civilians often includes "free-fall" between exiting an aircraft and the deployment of a parachute. During free-fall, the parachutist configures his/her body to maneuver through the air, adjust fall rate, and control lateral movement with respect to the ground. Military free-fall and civilian skydiving are performed in the "frog position," wherein the parachutist faces the earth, the back is arched, the pelvis is down, the arms are out with elbows bent, and the legs are bent at the knees with the feet extending upwards away from the earth. Bringing the feet up closer to the derriere will cause the free-faller to backslide. Extending the feet away from the derriere will cause forward movement. Extending the feet directly upwards away from the earth is called the neutral position and causes neither forward nor backward movement.
The object of military parachuting is to deploy troops within a specific zone, and is typically attained in one of the following two ways: high altitude, high opening (HAHO); and high altitude, low opening (HALO). During HAHO, a detachment exits an aircraft at high altitudes (typically exceeding 25,000 feet), deploys parachutes soon thereafter, and then drifts downward to the prescribed location. Depending on the winds, the detachment might be able to drift up to 18 miles in any lateral direction with respect to the earth. HAHO allows military personnel to deploy from the aircraft further from the target.
Unfortunately, winds at high altitudes can be unpredictable and make it difficult for all members of a detachment to land at the same location. In addition, deployment of parachutes at high altitudes requires a parachutist to be suspended within the parachute harness for long periods of time, often 20 to 30 minutes. This length of time often causes the legs and arms to fall asleep because of decreased circulation. Furthermore, high altitudes often cause parachutists to become very cold and requires oxygen for breathing. In addition, HAHO causes a parachutist to be more susceptible to detection because his/her parachute is open for such a long period of time.
HALO involves exiting from an aircraft at about 25,000 feet and free-falling to about 4,000 feet before deploying the parachute. The lateral distance with respect to the earth that a military parachutist is able to cover during free-fall is limited. Thus, HALO requires a military detachment to exit an aircraft that is relatively close to the target, thereby increasing the risk detection.
The civilian sport of skydiving involves various competitive aspects of free-falling, including: style, relative work, sit flying, sky surfing and free-style. Style is a competitive event in which the skydiver exits an aircraft at approximately 7,500 feet and then assumes a tuck position in which the face is to earth, the knees are drawn up towards the chest, and the arms are held tightly near the body. The arms, feet, and legs are used to help the skydiver perform "style set" which includes a 360.degree. right turn, a 360.degree. left turn, and a back loop. Each turn and back loop is repeated a second time for a complete style set, and the entire style set is performed as quickly as possible in a range of about 6 to 8 seconds.
Sit flying involves skydiving in a sitting position with arms extending out from the body for control purposes. Sky-surfing involves skydiving with a small surfboard strapped to the feet, and performing a preplanned series of maneuvers. Free-style involves performing various choreographic maneuvers. "Relative work" involves two or more skydivers falling relative to each other for the purpose of carrying out a preplanned set of maneuvers. These maneuvers involve turns, forward and backward movement, and side to side movement. Before a maneuver can occur, all of the skydivers must "dock" together. To do this, each skydiver must increase his/her fall rate in order to join the other skydivers. Therefore, it is necessary that each skydiver join the formation as quickly as possible to ensure enough time to perform the maneuvers. Unfortunately, skydivers fall at different rates depending on their height and weight.
Each of the above described civilian and military free-fall activities requires the ability to maneuver quickly and accurately. In addition, many free-fall activities involve multiple skydivers and multiple military parachutists in the air at any given time. It is understood that the terms "skydiver" and "skydiving" will be used hereinafter to refer to both civilian skydivers and civilian skydiving, and military parachutists and military free-fall. Collisions during free-fall can be fatal. It is especially important that each skydiver be aware of his/her position relative to other skydivers and be able to move quickly in whatever direction necessary to avoid a collision. Therefore it would be desirable to provide a way to enhance maneuverability, fall rate control, and lateral speed control.